Quora has more or less admitted that it doesn’t really need the $50 million it just finished raising, at least not yet. Co-founder Adam D’Angelo said (on Quora, of course) that more than half of the Series A funding round of $11 million the startup raised in 2010 is still sitting in the bank, unused. So why raise that much money at all? As Om has noted, one reason Quora did so is simply that it could — there was apparently plenty of interest, and the company wound up with financing from original Facebook investor Peter Thiel, among others.

Raising money is easy for Quora, so why not do it?

This is the startup version of the old adage “make hay while the sun shines,” and when two of your co-founders are Facebook alumni — Adam D’Angelo was the chief technology officer of the social network, and Charlie Cheever oversaw the development of Facebook’s “open graph” platform — there is plenty of hay to be made, especially since both founders are likely to become extremely wealthy when Facebook goes public (more than a third of the $50 million that Quora raised reportedly came from D’Angelo himself). More than anything, VCs love to give money to people who don’t need it.

D’Angelo has said that one of the reasons Quora raised the funding is so that it would have more “runway,” or room to prove itself and its concept before it has to start making money. And it’s clear, based on interviews with the founders, that the company sees what it is building as a potentially world-changing idea. Both seem devoted to it not because they believe it will be easy to flip or sell for billions of dollars (which they don’t really need), but because they think there is an interesting problem worth solving. As Cheever told me in 2010:

We’re not really focused on making money right now. I think if we can solve the problem we are trying to solve, we will find a way to make money.

In a nutshell, that problem is how to aggregate or crowdsource expertise on a wide variety of topics efficiently, and it’s one that any number of startups and services have tried to tackle, all the way from Yahoo Answers and Ask.com to Formspring, Reddit and Stack Exchange. And most have failed: Yahoo Answers and others have degenerated into cesspools of uselessness and spam, while companies like Aardvark disappeared inside Google and other acquirers, never to be seen again. Facebook launched its own Questions service in 2010, but there’s no sign that many people are using it much.

Among those who have tried to attack the problem from a different angle are sites like Demand Media’s eHow, which pays writers to come up with articles that contain some kind of expertise about a topic. Interestingly enough, eHow was built by Josh Hannah — who bought it in 2004 and built it into a major player before selling it to Demand Media, and is also an investor in an open-source spinoff called WikiHow. Hannah, now a partner with the venture-capital fund Matrix Partners, is an investor in Quora’s latest financing round.

Wikipedia is the model, but can Quora mimic its success?

Despite all the failures, there is one obvious example of a successful crowdsourced knowledge base, used by hundreds of millions of web surfers daily: Wikipedia. More than a decade after it was originally launched, the site is one of the top 10 most-visited web destinations on the Internet with 15 billion pageviews per month. And even more unlikely, Wikipedia has accomplished this feat without raising any venture-capital funding whatsoever, relying solely on donations and charitable funding.

The two sites have somewhat different approaches: Wikipedia asks users to contribute links and verified facts to articles that are designed to be a one-stop source of information about a topic — contributors are explicitly not allowed to state opinions based on their personal knowledge. Quora, however, tries to get those with knowledge to answer questions about specific topics, and then the community gets to vote on which answer they like best. Both sites have strict rules about what kinds of content can be posted, to avoid the Yahoo Answers problem. As a user of the site, I’ve found the quality of the answers to be consistently pretty high.

So the ingredients of a compelling story are there: founders who have their eye on a big vision, who aren’t motivated solely by a quick flip for cash, and who are trying to build a Wikipedia-style global knowledge database powered by individual input from experts. The fact that Quora’s usage numbers seem a little lackluster is the only fly in the ointment for believers — but then, there was a time when Wikipedia wasn’t really a household name either.